Name: Kinser Hair
Location: Indiana
What: L28E 280z-280zx factory replacement fuel injectors
Price: $100 OBO - Free Shipping withing the USA
Thank you for taking the time to look at my advertisement. I have for sale a set of six (6) factory replacement fuel injectors for an L28E. They were purchased from an Ebay vendor, I will provide a link to a sale of the same injectors below. I ran them for 3000 miles on my 1977 L28E with an all factory fuel system. They work flawlessly and were a much needed replacement for the tired injectors from the 70's. These injectors made a world of difference to the overall performance.
I am not responsible for being sure that these injectors will work with your specific year and vehicle. The injectors have no warranty given or implied, what you see is what you get. With that being said, as stated above, they only have 3000 miles of driving on them, and they worked excellent, I spun a bearing in my engine and went L28ET.
If you have any questions or concerned feel free to send me a PM or email me at Kinser(dot)Hair(at)gmail.com I will get back to you as soon as possible. I usually respond quickly.
Below is a link to the ebay auction mentioned above:
http://www.ebay.com/itm/75-76-77-78-79-80-81-82-83-Datsun-280Z-Fuel-Injectors-/150827663676?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3A280Z&hash=item231e07813c&vxp=mtr
Picture(Sorry its a little grainy, taken with gopro Hero3):

You should 100% defiantly remove the interior tar. Dry ice works well, or being that it is getting cold outside I would say go outside on a very cold day. Being in Florida might make this difficult, yes? If its rusted through enough to have a small hole there, there is more rust across the floor. A patch would be fine, but make sure you take the surrounding metal down to bare and be positive that there isn't any more rust, then prep the metal correctly to be sure there isn't any other rust left before primer and paint.

If you don't go glass I'm in Indiana and wouldn't mind a set of glass fenders. Then again I'm also wanting to build an AR15, so maybe I need to decided which I care about more. My metal fenders aren't rusty and look fine....
I'd go glass.

8.5" +10 will not fit a car with stock suspension, I highly doubt them to fit a car with 2.5" spring coil overs without spacers, but I could be wrong. I've got probably 1/4" - 1/2" clearance between the wheel and strut on factory 240z suspension with 8" wheel +0. 280z springs are larger if I am remembering correctly.

I'm running 3" exhaust and I just have it tucked as close to the differential as Six_Shooter stated above. In his second to last picture if you view the differential there, a little knuckle or tab or whatever you want to call it extends off the diff. Grind it off. It's not needed. Let's to tuck it up just a tad bit more and you don't have an annoying banging noise if your exhaust moves a little bit. Also if your exhaust rubs it too long there will be a hole there. Notice the marks from it in Six_Shooter's pictures.
Another thing that allowed me to tuck my exhaust up really high was the fact that I've got an RT diff mount and I took the factory diff mount that holds the control arms up, and section the middle out and boxed in the ends that hold the control arm up, that way they are still strong and do their job, but the diff mount is out of the way. Some will say I've sacrificed chassis strength. In my opinion the RT mount is adding any support I may have removed from the chassis right above, most likely more than I removed seeing as how its made of thicker steel. As far as clearance this gave me, when it comes down to it it only gave me more clearance in the transmission tunnel because I've got the exhaust higher in there. Really though that is where it was needed because that is where speed bumps and other things are most likely to hit the exhaust. Seeing as how the wheels are right in line with the spot that you're having troubles with, it will be going up as the wheels do on speed bumps.
Beyond that I would agree in saying either oval or square/flat tubing would be the only other way to get around that, short of cutting holes in the floor and running the exhaust inside the car and over that, which just sounds insane unless you're building a race car.